Bond Strength Stability of Different Dual-Curing Adhesive Cements towards CAD-CAM Resin Nanoceramic - An In Vitro Study

At a Glance

Metadata	Details
Publication Date	2021-04-27
Journal	Applied Sciences
Authors	Edoardo Alberto Vergano, Andrea Baldi, Allegra Comba, Edoardo Italia, Giorgio Ferrero
Institutions	University of Turin, University of Campania “Luigi Vanvitelli”
Citations	4
Analysis	Full AI Review Included

Executive Summary

This study evaluated the stability of the bond strength (µTBS) between three dual-curing adhesive cement systems and Cerasmart resin nanoceramic over a 12-month aging period in artificial saliva.

Core Finding (Cement): The choice of luting cement significantly affected immediate bond strength (p = 0.0002). Panavia V5 (Kuraray) achieved statistically higher µTBS values at baseline (T0) compared to Bifix QM (VOCO) and Estecem (Tokuyama).
Core Finding (Aging): Aging time (12 months) did not significantly influence the bond strength for any tested system (p = 0.0991), suggesting good hydrolytic stability across all groups.
Best Performance: Panavia V5 demonstrated the highest immediate µTBS (32.45 ± 7.71 MPa), attributed to its 10-MDP functional monomer and the use of a separate, fresh DC activator, promoting a higher degree of conversion.
Failure Mode: A prevalence of adhesive fractures was observed at the luting cement/Cerasmart interface across all groups and time points, confirming that the adhesive interface was the weakest link.
Material Composition: The Cerasmart CAD-CAM material is a resin-based composite containing 71% wt filler (20 nm silica and 300 nm barium glass nanoparticles).
Engineering Implication: The results support the long-term durability and clinical reliability of these dual-curing systems when used for luting indirect CAD-CAM resin nanoceramic restorations.

Technical Specifications

Parameter	Value	Unit	Context
Cerasmart Filler Content	71	% wt	Silica (20 nm) and Barium Glass (300 nm) nanoparticles.
Panavia V5 µTBS (T0)	32.45 ± 7.71	MPa	Immediate bond strength (Highest group).
Bifix QM µTBS (T0)	25.75 ± 7.65	MPa	Immediate bond strength.
Estecem µTBS (T0)	26.39 ± 6.69	MPa	Immediate bond strength.
Panavia V5 µTBS (T12)	35.55 ± 6.18	MPa	Bond strength after 12 months aging.
Aging Environment	Artificial Saliva	N/A	Storage temperature maintained at 37 °C.
Statistical Significance (Cement)	p = 0.0002	N/A	Significant difference observed.
Statistical Significance (Aging Time)	p = 0.0991	N/A	No significant effect observed.
Specimen Size (Beams)	1 x 1	mm²	Dimensions for microtensile testing (µTBS).
Sandblasting Pressure	1.5	bar	Used with 50 µm Al₂O₃ powder on Cerasmart slabs.
Light Curing Time	60	Seconds	Applied using a multi-LED lamp (Valo).
Testing Speed	~1	mm/min	Crosshead speed during µTBS testing.

Key Methodologies

Dentin Substrate Preparation: Thirty-six extracted molars were flattened to expose sound coronal dentin. A standardized smear layer was created using 600-grit paper.
CAD-CAM Material Preparation: Cerasmart blocks were sectioned into 4 mm slabs. Slabs were sandblasted (50 µm Al₂O₃ at 1.5 bar) and rinsed with pure alcohol.
Adhesive System Application (Cerasmart): Slabs were treated with material-specific primers: Clearfil Ceramic Primer Plus (V5), Bifix Ceramic Bond (QM), or Estelink Primer A+B (ES).
Adhesive System Application (Dentin): Dentin surfaces were treated according to manufacturer instructions for each group, including the dualization of the adhesive (e.g., Clearfil Universal Bond Quick mixed 1:1 with Clearfil DC Activator for the V5 group).
Luting and Curing: Dual-curing cements (Panavia V5, Bifix QM, Estecem) were applied, followed by 60 seconds of constant pressure application to simulate clinical seating, and then 60 seconds of light curing.
Specimen Sectioning: After 7 days of storage in distilled water (37 °C), specimens were serially sectioned using a low-speed diamond saw to obtain 1 x 1 mm beams (µTBS sticks).
Aging Protocol: Half of the beams were tested immediately (T0). The remaining half were stored for 12 months (T12) in artificial saliva at 37 °C to simulate long-term oral exposure.
Mechanical Testing: Beams were fixed using a Ciucchi’s jig and tested to failure using a microtensile tester at a rate of approximately 1 mm/min.
Failure Analysis: Fracture surfaces were examined under a stereomicroscope and Scanning Electron Microscope (SEM) to classify failure modes (Adhesive, Cohesive in Dentin, Cohesive in Cement, Mixed).

Commercial Applications

The findings are directly relevant to the manufacturing, selection, and clinical application of high-performance dental restorative materials and bonding agents.

Indirect Restorative Dentistry: Provides validated protocols for luting CAD-CAM fabricated restorations (crowns, inlays, onlays) made from resin nanoceramics (like Cerasmart) to dentin.
Dental Materials Manufacturing: Confirms the superior performance and hydrolytic stability conferred by 10-MDP based adhesive systems (Panavia V5), guiding the formulation of next-generation dual-curing cements.
Clinical Protocol Standardization: Establishes evidence that the chemical activation of the adhesive (dualization) prior to luting, as performed in the Panavia V5 protocol, yields higher initial bond strength, particularly critical for thick, light-attenuating restorations.
Long-Term Material Reliability: The acceptance of the null hypothesis regarding aging time confirms that all tested systems provide a bond interface stable against hydrolytic degradation over a 1-year period, supporting long-term warranty claims for these materials.
Adhesive System Selection: Engineers and clinicians can use the µTBS data to select cements that offer the highest initial bond strength (Panavia V5) when bonding to resin nanoceramic substrates.

View Original Abstract

Background: To evaluate different adhesive luting procedures on coronal dentin bond-strength of Cerasmart CAD-CAM blocks with μTBS test. Methods: 36 molar crowns were flattened in order to expose sound dentin and a standardized smear layer was created with 600 grit paper. Specimens were divided into six groups according to the luting cement employed (n = 12 each): G1: Panavia V5 (Kuraray, Japan); G2: Bifix QM (Voco, Germany); G3: Estecem (Tokuyama, Japan). CAD-CAM blocks (Cerasmart, GC), shade A2LT, size 14, were sectioned with a diamond saw to obtain 4 mm high specimens, which were then luted on the coronal dentin, following the manufacturer instructions. Specimens were serially sectioned to obtain 1 mm thick beams in accordance with the μTBS test technique. Half of the beams were stressed to failure after 24 h (t = 0), while the other half were stored in artificial saliva for 12 months, at 37 °C, for ageing before stressing to failure (t = 12). Results: two-way ANOVA test showed significant difference for the factor “luting cement” (p = 0.0002), while the factor “time of storage” (p = 0.0991) had no significant effect on µTBS. Conclusions: PanaviaV5 seems to have better µTBS values at T0 than QM and ES and 1 year aging doesn’t seem to affect the bonding strength of tested systems.

Tech Support

Original Source

DOI: https://doi.org/10.3390/app11093971

References

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